Exercises

Prove the following properties:

1. length (l1 @ l2) = (length l1) + (length l2)
2. length (map f l) = length l
3. map f (l1 @ l2) = (map f l1) @ (map f l2)
4. map (f1 >> f2) l = map f1 (map f2 l)
5. filter p1 (filter p2 l) = filter p2 (filter p1 l)

answers